Brexit will officially happen at 11pm on the day Article 50 runs out, the Government has signalled.
The move means Britain's historic divorce will fall at midnight, Brussels time, on 29 March 2019.
It will be officially enshrined in the EU Withdrawal Bill, after the Government announced it was amending the key legislation to make the issue "crystal clear".
Sky News understands ministers are doing so to acknowledge an opposition amendment and avert further hold-up of the crucial bill.
Brexit Secretary David Davis said the change was being made to "remove any confusion or concern about what 'exit day' means".
"This important step demonstrates our pragmatic approach to the vital piece of legislation," he declared.
It comes as the Government wades through hundreds of amendments to its key Brexit law, attempting to solve changes backed by some of its own MPs before letting it progress further through Parliament.
Sky's Robert Nisbet said: "This is the Government throwing some red meat to Brexit-supporting MPs on both sides of the house.
"It's the Government sounding tough with those who would frustrate the process: Britain is going to leave the EU, and even a little earlier than expected, taking the time difference into account.
"They'll be hoping that will placate the Brexiteers when the Government is expected to back down over several controversial measures in the bill, which have attracted hundreds of amendments.
"Those include using so-called 'Henry VIII' clauses to make changes to the bill without going back to Parliament."
Prime Minister Theresa May had declared in her Brussels speech that Brexit would officially happen on 29 March 2019 – two years from the date when she triggered Article 50.
But when her spokesman was asked earlier in the year for the exact divorce timing, they replied: "It's when Big Ben bongs at midnight" during the first second of 30 March 2019 in Europe.